Type-writer platen.



0. F. MULLER.

TYPE WRITER PLATEN.

APPLICATION FILED JULY 7. I917- MM Jan. 22,1918,

OSCAR F. Ml 'IiLER, F DOBCHESTEE, MASSACHUSETTS, ASSIGNOR TO THOR]? 8; MARTIN TYPEWRITER 00., 0F BOSTON, MASSACHUSETTS, A CORPORATION OF MASSACHU- TYPE-WRITER PLATEN.

Application filed July 7, 1917.

' tain new and useful Improvements in Type- Writer Platens, of which the following is a specification.

This invention relates to platens for typewriters, adding machines and the like, and particularly to a platen of the so-called noiseless type. the same beingconstructed in a manner in which a deadening of the sound of the type shock iseifected.

Various efforts have been made with more or less success to accomplish this result in a practical platen adapted for commercial manufacture and actual service use. While some deadening effect has been produced by different devices one of the great difficulties has been to. devise a platen which could be produced in quantity and by convenient methods and which would have a maximum degree of silence while maintaining a sufficient rigidity of structure.

The problem of securing a rigidity of structure without involving a degree of density which would make for noise has been a diflicult one. A great variety of materials have been employed and it has;

usually been found necessary to employ a dense or rigid structure and then attempt to silence it by packing. The matter of packing has been diflicult from a commercial point of view inasmuch as the filling of a pack to secure any degree of uniformit has been difficult and furthermore such pac has had a tendency to sag or settle.

Among packings which have been favored, have been those of fibrous material such as cotton. This has been variously applied either as a stufiing or in the form of fabricatcdfiber which in some instances has been wound into layers or shells forming strata of the roll.

Throughout these various structures there has been, so far as I am advised, an inherent diihculty in that the material, if stratified,

contained one or more strata forming a dense and therefore resonant la er, which acted independently of the dea ening lay-' 'T ers.

If unstratified there was either a lack Specification of Letters Patent.

Patented Jan. 22,1918.

Serial No. l79,153.

of strength or a lack of uniformity or both. In my invention I secure exterior strength and rigidity suflicient to bear the actual type contact surface with a progressive decrease of density so that any vibration set.

up is led in and progressively absorbed toward the center before it can reach the shaft and thus be transmitted to the rest of the machine. The construction and utility of my invention will be more fully disclosed in the specification which follows. In the drawings I have shown a form of typewriter platen which I have found suitable for practical use and well adapted to manufacture. Throughout the drawings and specification like reference numerals are correspondingly employed and in the drawing:

Figure 1 is a transverse sectional view of a typewriter platen in accordance with my invention.

Fig. 2 is a longitudinal section, and

Fig. 3 is a similar view of a platen also in accordance with my invention, but representing slightly different structure from that indicated in Fig. 1. I

Referring to Fi 1 my roll consists of the usual outer she I 1 of hard rubber within which is-a core body 3 of progressively decreasing density from thesurfac'e inward treated to produce a decreasing density from the surface inward, but as found in practising my invention, a core may be advantageously made by winding under suitable tension a strip of fabric such as cotton cloth upon a thin inner shell 4 which latter forms the openin for the platen shaft.

The core is t on treated to produce a progressively decreasing density from the surfaceinward. A very simple and inexpensive manner of efi'ecting this treatment is by immersion of the core in a bath of hot paraffin, the time of immersion necessary for penetrating gradually and in a diminishing degree toward the interior of the rolls depending upon, the density of the fabric employed and the degree to which the molten paraiiin is heated. By limitingthe impregnation to the outer layers of the core an elastic cushion is formed by the flexible fabric of the inner layers and the air inclosed by the surrounding impregnated external portion. In Figs. 2 and 3 I have indicated at 3 by lines of progressively decreasing heaviness inwardly a core formed by thus windmake a good carrying core for the exterior shell. I findfurther in the practice of my invention that a wire shell or cage 2 as shown in Figs. 1 and 2, may be conveniently embodied with the core by placing on said core prior to immersion. This further unifies the structure and adds to the elasticity of the core.

Various modifications may obviously be made in the materials, the degree and extent of impregnation and manner of assembly employedin my invention, all without parting from the spirit thereof, if within the limits of the appended claims.

What I therefore claiin and desire to secure by Letters Patent is:

1. A platen core of the class described comprising an, impregnatable body decreasingly impregnated from the surface inward with a sound-deadening agent.

2. A platen core of the class described comprising a. fibrous impregnatable body with a sound deadening agent.

decreasingly impregnated from the surface inward with a sound-deadening agent.

3. A platen core of the class described, comprising a'body of fabricated fiber wound upon itself and decreasingly impregnated closing said core and included in said impregnation and a type shell lodged thereon. 6. A platen core of the class described, comprising a fibrous body decreasingly i1npregnated from the surface inward with a waxy filler.

7. A type platen core consisting of an impregnatable body decreasingly impregnated 8. A type platen core consisting of a fibrous body, and decreasingly impregnated with a sound absorptive agent in a liquid statewhich agent is adapted to be hardened by exposure to atmosphere.

9. A type platen core consisting of a body of stratified material decreasingly impregnated with a sound-deadening agent adapted to unifythe strata of the stratified body.

In testimony whereof I afiix my signatur in presence of two witnesses.

OSCAR F. MULLER. Witnesses:

VICTORIA LowDEN, AGNES V. OCONNELL. 

